Telephone system



April 5; 1932- J. w. GODERHAM 1,852,647

TELEPHONE SYSTEM Filed June 6, 1930 /NVE/VTUR J W GUDDERHAM PatentedApr. 5, 17932 UNITED STATES PATENT OFFICE p JOHN W. GOODERHAM, OFLARCH'MMONT, NEW YORK, ASSIGNOR TO BELL TELEPHONE LABORATORIES,INCORORATEDLF NEW YORK, N. Y., A CORPORATION OF NEXV Yom:

TELEPHONE SYSTEM Application nea June e, 1930. seriaino. 459,515.

This invention relates to telephone systems and particularly to theidentification of the calling station on a party line.

The objects areto enable the performance of a speedy and reliable testof a party line to ascertain the calling substation, to enable this testwithout encumbering the line with ground or other interferingconnections during conversation, and to otherwise improve systems ofthis character.

According to this invention, each of the substati'ons on a four-partyline is equipped with an alternating currentrelay selectively responsiveto current of a particular frequency. vThe central office is providedwith four sources of alternating current, each of a frequencycorresponding to'one of the substation relays, together with means forapplying these sources in succession to the line to make the identifyingtest. When the source corresponding to the relay at they call-v Theinvention is illustratedin the ac`com' panying drawing, which shows aparty line terminating in a line .finder switch together with means atthe central ofl'ice for performing the identification tests and forselectively 5 operating the message registers. i n

The subscribers line 21 has vfour substai tions A, B, C and D. Thesestations are equipped respectively with alternating current responsiverelays 1, 2, 8 and 4. These i0 relays are inductively connected to theline by means of the transformers 5, 6, 7 and 8 `respectively. Eachrelay attracts its armature in response to alternating current of` apar` ticular frequency, which differs' from the fre- .quency to whichVany of the other relays is responsive. At the central ofhce the lineter- `minates in the bank of a line finder switch F, which isdiagrammatically illustrated by the brushes 22 to 28 inclusive.U Theline finder ,F is directly connected' to a selector switch S having thebrushes 65, 66 and 67, which is also illustrated in partdiagrammatically. The selector switch S has access to succeedingselectors (not shown). v

The line finder and selector disclosed in this system may be of thepanel type similar to the one described in the patent to Craft et al.,No. 1,123,696, granted January 5, 1915. The control and operatingcircuits for a selector switch of this character are shown and describedin detail inthe patent to Kopp No. 1,589,402, granted June 27, 1926, andalso shown in the patent to Stern et al., No. 1,395,- 977, grantedNovember 1, 1921.

The stations A, B, C and D are provided at the central office withindividual message registers 62, 62, 63 and 64, which are selectivelyoperated to assess calls againstV the corresponding stations on theline. The registers are selected as the result of an identication testperformed at some convenient time after the subscriber initiates thecall. The test is madel by meansof the alternating current sources 52,53,154 and' 55, each of a different frequency, and the results of thistest are recorded on the relays 57, 58, 59 and 60.

A detailed description will now be given, and it will be assumed forthis purpose that the subscriber at station A initiates a call. Inresponse to the initiation of the call, the line finder F operates toseize the calling line 21. Thereupon, the subscriber manipulates hisimpulse transmitter 9 to set up the called designation in a registersender (not shown) at the central office. The register sender proceedsto control the selector switch S and ,succeeding switches to extend theconnection to the called subscribers line as is fully described in theabove-mentioned patents to Kopp and to Stern et al.

' When the called party answers, the direction of current flow over thetrunk with whose terminals the brushes 65, 66 and 67 of the selector Sare in contact, is reversed, thereby causing the operation of thepolarizedsuper- Vvisory relay 33. `At this time the sequence switch hasadvancedto some position such as position 13, in Awhich it remainsduring conversation. As soon after ,the relay 33 operates as theinterrupter 44 closes its right magnet 46 to control the testing of thelinel through conductors 72 and 73 tothe subcontacts, a circuit iscompleted from battery through the winding of relay 34, right contactsof said interrupter, contacts of sequence switch spring 38, contact ofrelay 33, upper contact of sequence switch spring 38, contact of relay33, upper contact of sequence switch spring 35, to ground at the Contactof sequence switch spring 36. Relay 34 operates and locks through itsupper contact, contact of sequence switch spring 37, thence as abovetraced to ground at sequence switch spring 36. As soon after relay 34has operated as the interrupter 44 closes its left contacts, a circuitis completed from battery through the winding of relay 29, uppermostcontact of relay 31, contacts of sequence switch spring 68, lower frontcontact of relay 34, left contacts of interrupte'r 44, thence as abovetraced to ground at sequence switch spring 36. Relay 29 operates andlocks in a circuit from Ybattery through its winding, uppermost contactof relay 31, inner lower contact of relay 29 and contact of relay 33 toground at sequence switch spring 36.

The brushes 47 to 51 inclusive of the stepping switch S-1 are nowadvanced by the alternate operation and release Vof the stepping 21.With the brushes in any one' of positions 1 to 8 inclusive, position 1being the normal position, a circuit is closed, after relay 29 isoperated, through the winding of the magnet 46 each time thecontinuously driven interrupter 30 closes its contacts. This circuit maybe traced from `battery through the winding of the magnet, brush 48,positions 1-to 3, conductor'69, innerupper contact of relay 29 to groundat the contacts vof the interrupter 30. The release of the magnet 46each time the circuit is opened causes the advance o f the brushes onestep. After the brushes are advanced beyond position 8, theV magnet 46is no longer under the control of the interrupter 30.

With the stepping switch S-Y-l in position 2, a circuit is closed frombattery through the lower winding of relay 32, brush 49, conductor 70 toground through sequence switch springs and 36. Relay 32 operates andlocks through its lower winding and inner lower contact to the groundedconductor 70. Relay 32 prepares a'circuit for: operating the callingsubscribers message register after conversation has been completed. Y

With the stepping switch in position 2, 'another circuit is closed fromthe grounded source ofalternating current 52 through the brush 50,primary winding of the transformer 7,1 to ground. The secondary `windingof the transformer 71 lis connected scribers line 21.v The circuit overthe subscribers linemay'be traced vfrom the -rightthand terminal'oflthesecondary winding of said transformer overrconductor 72, :upperhandterminal of the secondary winding of transformer 71. Current flowingfrom the source 52 through the primary winding of transformer 71 inducescurrent of the same frequency in the secondary winding and this currentflows over the subscribers line and through the transformer 5. It willbe assumed that the frequency of source 52 is such as to cause theoperation of relay 1 at the calling substation vA. Relay 1 operates andcompletes a circuit from ground through its armature and contact overthe tip conductor 74, thence as above traced to conductor 72, through aportion of the secondary winding of transformer 71 through 'the windingof relay 56 to battery. A parallel circuit is completed from thegrounded armature of relay 1 through the transformer 5 and inductioncoil 10, switchhook contact, talking transmitter and impulse transmitter9 over the ring conductor 75, thence vto conductor 1 73 and 4through theother Aportion of the secondary winding of transformer 71 and thewinding of relay 56 vto battery. Relay 56 operates in this circuitandcloses a circuit from ground through its armature and contact, brush51 in position 2, conductor 76, winding of the register relay 57 tobattery. Relay 57 operates and locks 'in a circuit from battery throughits winding and left contact, conductor 77, to ground at the lowercontact of relay 32.

The stepping switch S--lcontinues'its ad- Vance through positions 3,4,5, 6, 7 and 8 and in so doing applies the sources-53, -54 and insuccession to the transformer 71. However, this is without effect sincetherelay 1 responds only to the source 52 andfsince only the substationA is calling.

When 'the stepping'switch S-1 reaches position 9, a circuit is closedfrom battery through the winding of relay 31, brush 49, to the groundedconductor V70. Relay 31 opcrates and locks to conductor 70. Relay 31 atits uppermost contact opens the circuit of relay 29, and this relayreleases. Relay 31 in operating connects ground potential through itsinner upper contact overconductor 78, contact and arma-ture of 'magnet46,

brush 47 is associatedareconnected together the switch continues toadvance `until it has reached its normal position 1. The apparatusremains in this position during conversation.`

When the called subscriber replaces his receiver on the switchhook,relay 33 releases, and sequence switch 45 is advanced from the talkingposition to some subsequent position, suchas position 17, to cause theoperation of the message register of the calling The release of relay 33opens the circuit of relay 34, and the latter relay releases. Relays 31and A32 are'now held in a circuit though their windings and lockingcontacts, conductor 70, back contact of relay 34, brush 47, position 1,armature' and contact of the magnet 46, conductor 78, through the innerupper contact of relay 31 to ground. While the sequence switch 45 isadvancing from position l to position 17, a metering circuit is closedfrom battery through the Vresistance 79, upper contact of relay 32,contacts of sequence switch spring 80, lowermost contact of r-elay 31,conductor 81, right-hand armatures and back contacts of relays 60, 59and 58 in series, right armature and front contact of relay 57,

V brush V28, through the winding of message register 61 to ground. Theregister 61 operates and charges the call against substation A.

When the sequence switch reaches position 17 and as soon thereafter asinterrupter 43 closes its contacts, a circuit is completed from battery,through winding of relay 34, contacts of sequence switch springs 41 and42 to ground at the contacts of interrupter 43. Relay 34 operates andopens the holding circuit of relays 31 and 32. Relay 34 may be heldenergized in the manner shown in detail in the above-mentioned patent toKopp to permit the release of relays 31 and 32 as the sequence switch 45advances to subsequent positions. The release of relay 32 opens theholding circuit of relay 57. From this point, the release of the linefinder and selector switches takes place in any well-known manner, suchas explained in the above mentioned patents to Kopp and to Stern et al.

Assume next that the call is initiated at substation B. In this casetherelay 56 does not operate when the stepping switch moves into position 2since current induced by the source 52 does not cause the operation ofrelay 2 at the calling substation. In position 4 of the stepping switchhowever, current from the source 53 is connected to the transformer 71,and the induced current in line 21 is of the proper frequency to operatethe relay 2 at substation B. Relay 2 applies ground potential to the tipand ring conductors of the line 21 in the manner already explained inconnection with substation A, and relay 56 operates. Relay 56 appliesground potential over brush 51, conductor 82, winding of relay 58 tobattery. Relay 58 operates and locks through its left contact to thegrounded conparty. holding ter 64 operates and charges the call tosubstation D.

duetor 77. The switch S-l continues to step, and sources 54 and 55 areconnected to the transformer 71, butnothing further happens since thesesources are not of the proper frequency to operate relay 2. At the endof con-37.n versation when the sequence switch 45 is passing fromposition to position 17, the metering circuit is completed from batterythrough the resistance 79, thence as traced over cony ductor 81, rightbaclr contactsof relays 60 anda, 59, right front contact of relay 58,brush 27, winding of message register 62 to ground. The register 62operates and charges the call to substation B.

Assume next that the call is initiated byxf substation C. In this casenothing happens when the sources 52 and 53 are connected to thetransformer 71. However, when the stepping switch S-l reaches `position6, source 54 is connected to the transformer and the current induced inthe line 21 is of the proper vfrequency to operate relay 3 at thecalling substation C. Relay 3 causes the operation of relay 56asexplained, and relay 56 completes a circuit over brush 51, conduc-tm tor83, winding of relay 59 to battery. Relay 59 operates and locks throughits left contact to the grounded conductor Y7 7. Subsequently, when thesequence switch is moving from position 15 to position 17, the meteringcir-CL cuit is completed over conductor 81, right back Contact of relay60, right front contact of relay59, brush 29, winding of messageregister 63 to ground. The register 63 operates and charges thecall tosubstation C. '515.100

Assume finally that the call is initiated at substation D. In thisinstance, the stepping switch first applies the sources 52, 53 and 54without effect. As the switch reaches posi-I tion 8,-source is connectedto the trans-:mi former 71, and the current induced in the line 21 is ofthe proper frequency to cause the operation of relay 4 at substation D.Relay 4 applies ground potential to the line to cause the operation ofline 56. Relay 56 closes alim circuit from ground over brush 51,conductor 84, through the winding of relay to battery. Relay 60 operatesand locks to the grounded conductor 77 As the sequence switch 45 passesfrom position 15 to position 17, the metering circuit is completed overconductor 81 to the right front contact of relay 60, brush 25, windingofregister 64 to ground. Regis- While the invention has been illustratedin connection with a particular type of system,

it is to be understood that it is not so limited but may be embodied vinvarious kinds of systems. 'l 125 What is claimed is: i

' 1. In a telephone system a line having a pluralityof stations thereon,relays, one at each. station, said relays being responsive each tocurrent of a different frequency,

fir

plurality or stations thereon, relays, one at means for applying to saidline currents 'of different frequencies, and means controlled bytheoperation of said relays for identifying said stations.

2. In -a telephone system a line having a each station, said relaysbeing responsive each to alternating current of a dilierent frequency, aplurality of sources of alternating current, each of a differentfrequency, means for connecting said sources to said line, and meanscontrolled by the operation of said relays for identifying Isaidstations.

3. The combination in a telephone system of a line having a plurality ofsubstations thereon, relays, one at each of said stations,

Ieach of a frequency .corresponding to said relays being responsive eachto alternating current of a different frequency, va plurality of sourcesof alternating current, one of said rela-ys, means for successivelyapplying .said sou-roes yto said line in a 1definite order, and vmeansresponsive to the operation of any one of said relays for identifyingthe cor- Q5 responding substation.

'5&0 current'of .a different frequency,

VM585 ing substation in said test circuit, means for connecting saidsources of current to said test circuit, and means responsive to theoperation of one of said relays in lthe test circuit Vfor identifyingthe corresponding substation. .5. In a telephone system a subscribersline having ka plurality of substations thereon, relays, one at each ofsaid stations, Vsaid relays being responsive each Yto alternatingcurrent .of a different frequency, message registers, one for each ofsaid substations, a plu- :ralityfof sources ofalterna'ting current, eachof a frequency cor-responding to one of said relays, mea-ns :forapplying 'said sources to the line in succession, means controlled bysaid relays for identifying the calling substation, ,and meanscontrolledA by the identifying means for Vselectively operating themessage register individual to the calling substation. y6. In `atelephone system, a line having a number of stations thereon, relays,one at each .of said stations, said relays being responsive each tocurrent of a. different frequency, a number of sources of current. eacnof a different frequency, means 'for connecting said sources to the lineto selectively operate the relay at thecalling station, said relays `in4operating serving to yapply potential `to said line,;and meansresponsive to the ap- -`plication of :potentials'by said relays to said:line vfor identifying said stations.

7. In a telephone system, a line having a plurality of stations thereon,relays, one at each station, said relays being responsive each tocurrent of a different frequency, a test circuit including theconductors of said line, means under the control of a calling subscriberfor closing the test circuit to render effective the relay at thecalling substation, means for selectively operating said relays,circuits closed by said relays in operating for applying groundpotential to said test circuit, and means responsive to the applicationof ground potential to said test circuit for identifying said stations.

8. The combination in a telephone system of a line having a plurality ofsubstations thereon, relays, one at each of said stations, said relaysbeing responsive each to -alternating current of a different frequency,a pluralit-y of sources of alternating current, each of a frequencycorresponding to one of said relays, means including a step-by-stepswitch for successively applying said sources to said line in a definiteorde-r, and means responsive to the operation of any one of said relaysfor identifying the corresponding substation.

In Witness whereof, hereunto'subscribe my name this 4th day of J une,1930.

JOHN W. GUODERHAM

